1. Field of the Invention
The present invention relates to self-propelled, non-riding trenching machines, and more particularly to self-propelled, non-riding trenching machines utilizing hydraulic steering mechanisms.
2. Prior Art
Typically, self-propelled, non-riding trenching machines range in weight from approximately 400 pounds to in excess of 1300 pounds and therefore are difficult to maneuver solely by the strength of the operator. These trenching machines have a single or double front wheel mounted on a chassis that is either freely pivoting or rigidly fixed so that it cannot be turned at all. In order to turn a trenching machine with a freely pivoting front wheel, it is necessary for the operator physically to turn in the trenching machine; the pivoting front wheel will then turn as the machine turns.
For those trenching machines that have a rigidly mounted front wheel, the operator must press down on the handle grips to raise the front wheel off the ground and pivot the entire trenching machine on the rear two wheels. This turning operation is difficult and clumsy, even with a well-balanced trenching machine. Indeed, since the operator must utilize his own body weight to press down the machine in order to raise the front wheels for turning, it is often impossible for a person weighing less than 150 pounds to turn a large machine.
When the trenching machine is in use digging trenches, sometimes it is necessary to turn the machine gradually as the trench is being dug in order to dig a curved trench. Therefore, it would be necessary for the operator to gradually turn the trenching machine as the digging process is underway. This gradual turning is extremely difficult if not impossible with both the fixed front wheel and pivoting front wheel trenching machines.
Therefore, there is a need for a trenching machine which has a steering mechanism which can turn the front wheel so that the operator does not have to rely upon his physical strength alone to tilt back or turn a heavy machine. In addition, it is desirable to have a steering mechanism which can gradually turn the trenching machine while the digging process is under way so that it can dig a curved trench. Such a steering mechanism also should require the use of only one hand so that an operator can use his other hand to grasp the trenching machine or to operate other controls.